METHOD AND APPARATUS FOR LITHOGRAPHIC IMAGING

A method of compensating for focus deviations on a substrate on which a plurality of layers are present includes generating a focal length predictor map (108) for the substrate. In one method, a focal length prediction map for the substrate is generated by obtaining key performance indicator (KPI) data (106) on the substrate using an alignment sensor, determining a correlation between the KPI data and focus offset data (102) for a location on the substrate, and using the correlation and the KPI data. In another method, the prediction map is generated by obtaining a first layer height map for a first layer, measuring a second layer height map for a second layer covering the first layer with a level sensor, and subtracting the first height map from the second height map to obtain an incremental height map for the substrate. 一种补偿衬底上的聚焦偏差的方法，在所述衬底上存在多个层，所述方法包括产生用于所述衬底的焦距预测图(108)。在一种方法中，通过使用对准传感器获得所述衬底上的关键性能指标(KPI)数据(106)，确定所述KPI数据与所述衬底上的位置的聚焦偏移数据(102)之间的相关性，以及使用所述相关性和所述KPI数据，产生用于所述衬底的焦距预测图。在另一方法中，通过获得第一层的第一层高度图、利